What free tools do you use?

I am trying to document some best practices around the top 10 - 15 free Web tools & services in terms of ease of implementation, use and return on investment (in either readership or revenue.)

So - if you are using anything from AudioBoo to Zeemaps - I would like to hear about your experiences and successes.

http://www.kiesow.net/webtools

Take a look at this quick survey if you want to take part. The end result will (hopefully) be a live session or webinar @Poynter.

Thanks

Damon